The present invention relates generally to application of suction for medical treatment. Therapeutic application of suction to the body can be used to treat a wide range of conditions, including, for example, muscular, pulmonary, lymphatic and circulatory conditions. In some embodiments, the invention can specifically be adapted for sleep breathing therapy, and more specifically, to provide apparatuses and methods for treating sleep disordered breathing, such as snoring, upper airway resistance syndrome and obstructive sleep apnea, with suction.
There is an ongoing unprecedented global pandemic of obesity resulting from radical changes in lifestyle. In addition, advances in medicine and public health have reversed the morbidity and mortality of many infectious diseases, resulting in longer human life expectancies. The obesity crisis transcends age, gender, cultural and socio-economic lines, and is resulting in tremendous increases in obesity related illnesses such as high blood pressure, diabetes, heart disease and obstructive sleep apnea (OSA).
OSA is a breathing disorder caused by excess fat deposition around the throat and neck that compresses the upper airway when an obese person lies down. During sleep, this causes snoring and recurrent interruption of breathing due to periodic obstruction of airflow at the level of the trachea (windpipe) during inhalation. Repetitive sleep disruption by abnormal breathing leads to chronic sleep deprivation that manifests as daytime fatigue and sleepiness, driving and work related accidents, and lower overall productivity.
OSA affects millions of people globally, most of whom are not treated due to poor access to diagnostic centers and the prohibitively high price of diagnosis and treatment using the best current technology. Medically significant OSA is thought to affect 24% of adult males and 9% of adult females in the United States. Most of these individuals have mild disease, and it is estimated that 75% or more are undiagnosed. Results from a 2005 poll done by the National Sleep Foundation using the Berlin Questionnaire indicate that as many as one in four American adults are at high risk for OSA. These statistics do not include minors; however, increasingly, OSA is being diagnosed in overweight children.
A minority of these patients have been diagnosed and treated due to a general lack of awareness of this health problem, especially since OSA in children tends to manifests as hyperactivity rather than daytime sleepiness. In addition, African-Americans and Asians are at greater risk for sleep apnea, but all the reasons for this have not been identified. Some non-obese patients also have OSA due to abnormal collapsibility of the trachea.
The health consequences can be serious or even life threatening in those with severe OSA. Low blood and tissue oxygen levels caused by cessation of respiration trigger the release of stress hormones like cortisol and adrenaline. These chemicals cause harmful surges in blood pressure, heart rate and blood sugar. Repetitive cycles of this process may lead to a stroke, heart attack or sudden death.
The current state of the art in treating OSA involves the life-long use of mechanical systems that pump air (sometimes enriched with oxygen) into the trachea via a mask that fits tightly over the nose, mouth or both. This pressurized jet of air called CPAP (Continuous Positive Airway Pressure) counteracts the collapse of the trachea from the weight of fatty tissue deposited over it. This technology is effective, but has the disadvantages of being expensive to purchase and maintain, and uncomfortable and impractical to use. The overall long-term compliance with CPAP is low, and usually only those with the most severe symptoms continue treatment.
OSA can be reversed by major weight loss, but this rarely happens without stomach reduction or bypass surgery that is usually reserved for the most obese patients. Consequently, OSA treatment is usually for life. Less radical surgery involves removing the sagging tissues in the nose and throat, and carving away the back of the tongue to create room for airflow. This procedure has been proven to work in only the mildest forms of OSA. The other approach has been to insert dental prosthetic devices in the mouth during sleep to prevent airway collapse, but again only mild cases respond, and these devices are uncomfortable and may damage the oral cavity.
Recent human clinical research has demonstrated that the critical pressure at which the trachea collapses and limits flow to a maximal level (Pcrit) is a measure of airway collapsibility and depends on the stability of the walls defining the upper airway as well as the surrounding pressure. Pcrit is defined as the pressure inside the upper airway at the onset of flow limitation when the upper airway collapses. Pcrit may be expressed as: Pcrit=Pin−Pout where Pin=pressure inside the upper airway at the moment of airway collapse; and Pout=pressure outside the upper airway (atmospheric pressure).
One approach to treatment of snoring and sleep apnea by using a non-CPAP medical device applying negative pressure in the region of the neck is disclosed by U.S. Pat. Nos. 5,343,878 and 5,592,938. Scarberry et al.'s sheath with a vacuum space does not, however, provide guidance as to device construction for comfortably controlling the application of suction and tissue distension.
An urgent need remains for an effective, controllable and comfortable treatment modality for obstructive sleep apnea.